error could not send or receive poplock busy

Some old email servers will intermittently give you the error "poplock busy".

This poplock busy error means that you were trying to get your email at the same time someone else was sending you an email.

Modern mail servers typically don't have this issue, but if you do run into it (as I just did while helping someone...) the best thing to do is shut down your mail program and try again a few minutes later.